1. Field of the Invention
This invention relates to high molecular weight terpolymers of maleic anhydride (MAN), C.sub.1 -C.sub.4 alkyl vinyl ethers (AVE), and isobutylene (IB), and, more particularly, to a solvent-free process for making such terpolymers.
2. Detailed Description of the Prior Art
U.S. Pat. No. 5,037,924 described the preparation of terpolymers of maleic anhydride, a C.sub.1 -C.sub.4 alkyl vinyl ether, and isobutylene, for use as denture adhesives in the form of their mixed salts. These terpolymers were made by precipitation polymerization in the presence of an added solvent, for example, a cosolvent system of ethyl acetate and cyclohexane. The resultant terpolymer had a low molecular weight of about 30,000 to 400,000, with relatively good performance, in the form of their mixed salts, as denture adhesives. Furthermore, the terpolymers and their salts made therein in U.S. Pat. No. 5,037,924 contain trace amounts of the ethyl acetate and cyclohexane solvents.
Accordingly, it is an object of this invention to provide a solvent-free process of making high molecular weight terpolymers of MAN, an AVE and IB.
A specific object herein is to provide such terpolymers with molecular weights of at least about 1,500,000, which, in the form of their mixed salts, perform in an excellent manner as denture adhesives.
These and other objects and features of the invention will be made apparent from the following more particular description of the invention.